So I've just been out for a run and recorded it on all the different platforms. My Fitbit charge 2 says 5.88 miles, my garmin 220 says 6.2 miles. On my iPhone 6s Strava says 6.3 miles and MapMyRun says 6.47 miles! Who on earth am I meant to believe??!! ???? I'd hope that my garmin is the most accurate as it's a dedicated GPS tracker but when hubby and I run together his garmin 205 never gives the same distance as mine! Is there anyway of finding out exactly how far a distance is or working out which device is most accurate? Thanks ???? Lucy
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I believe races are still measured by a bloke walking them with a wheel, so they are accurate. Why not run a measured 10K race, with all your various tech devices and see which is the most accurate, if any.
and very good luck with that.
None of them are entirely accurate, at the end of the day. You could take them all to a track, run 10 laps and odds are none of them will read 4.0 km.
For a start, they're not necessarily getting the same signals - the garmin may use Glonass as well as GPS, and any device may pick up different satellites. Any reading of position has a margin of error - locating you to within 10m may be accurate enough for knowing where you are in the world, but when you're using those readings to calculate speed and distance the errors add up. Most devices use some sort of smoothing to eliminate those errors, but garmin and strava process the raw data in different ways.
If you've got a traditional bike computer that uses a magnet to count wheel revolutions then that can give you a better idea of distance travelled for comparison, but of course that needs to be set up properly as well.
Or, you could not worry about it too much - if you stick to the same device you won't go far wrong. An hour's hard run is a hard run no matter how far it is.
I ran my PB 10k by 3 minutes a few weeks back. According to my fenix 3 i stopped the clock at 10.1k but when it sent to strava it only recorded at 9.9k and missed out on my PB. Don't know how that one happened being as it was my fenix 3 that told strava the distance!
Looks like the 205 is most accurate of your devices.
On the one hand I shouldn't be bothered, as long as I'm happy with my times and the GPS is consistent in its in/accuracy,which it is.
But its particularly irritating if I'm training for a race (have only done a few 10k's) or want to compare times from different routes.
The difference can be .2 of a mile over 3.5 miles for example, which might not seem much, but when you look at the pace it can mean a 20-30 seconds a mile difference which is significant.
Your Tom Tom seems to over measure by a bit more so if you know what % that is then that's what you need to take into account when predicting your race time.